The pair teamed up with top genealogist Henry Louis Gates, Jr. for new TV special "Finding Your Roots" and he reveals they were not exactly thrilled with what they dug up.

The historian explains, "It turns out they share two things -- they both are descendants from people who owned slaves, and they are indeed distant cousins."

And they weren't the only celebrities shocked by findings from the past on the show -- crooner Harry Connick, Jr. discovered he had Confederate ancestors while "Iron Man" star Robert Downey, Jr. learned there was a gruesome murder in his family history.

Gates, Jr. adds, "We don't have any prior agreements with anyone (over what could be disclosed), and we just did the stories. We have a team of genealogists. We have different genealogists for different people -- some are more expert on African-Americans, some on Jewish people, some on Ashkenazi-Jewish people, some on Asian people. But whatever we find, we try to boil it down to three or four narrative arcs."

Continues Gates, Jr. "(We discovered) Robert Downey, Jr., two generations back ... (there was) a murder in his family. He had no idea. I'm getting him reading the headlines from the New York Times about the murder of these ancestors. Harry Connick, Jr. did not want to know he had Confederate ancestors, I'm sure. We tell them (stars) and it's a total surprise."